We're going to present a screenshot of the changes from the Under Development page after the jump, but just to make sure your appetites are whetted, so to speak (or type, I'm not actually talking) here's a detail: there will be a new battleground called the Isle of Conquest, a large scale siege between the Horde and the Alliance.
But wait, there's more!
"In order to prepare for a siege on Icecrown Citadel, players will be called by the Argent Crusade to test their mettle in the Coliseum. 5-player, 10-player, and 25-player challenges await inside." Emphasis most definitely mine. What does this mean? Will it be PvP or PvE? Are we talking a scaleable instance with a 5, 10 and 25 man version? Pure speculation on my part leads me to wonder if we'll see something like a Violet Hold style event, with random opponents spawning to fight a party or raid sized group, but as of now all I know is what you know. I'm really, really curious about this.